1. Field of the Invention
This invention is related in general to the field of distributed control systems. In particular, the invention comprises utilizing the Internet to monitor and control geographically distributed controllers. An Internet Hub is utilized to facilitate communications between Clients and controllers.
2. Description of the Prior Art
It is very common to use electo-mechanical devices to control any of a myriad of different types of equipment. For example, relays are used to close doors, motor drivers are used to turn fans, and optical switches are used to turn on street-lamps. These electro-mechanical devices, referred to as controllers, often can be quite sophisticated and capable of performing advanced algorithmic calculations. For example, heating, ventilation and air conditioning (HVAC) controllers often possess computer processors used to analyze and respond to their environment such as changes in temperature, pressure, and humidity. They can even develop efficient heating and cooling plans in response to anticipated weather patterns.
Controllers often have sensors that sample their environment and return values in the form of variables. For example, a controller used to activate a variable-speed exhaust fan may utilize a temperature sensor to report the ambient air temperature in a room. Additionally, controllers have operating parameters that control their behavior. In the example of the variable-speed exhaust fan, the controller may be set to activate a fan when the ambient air temperature exceeds 90 degrees and linearly increase the fan speed as the temperature increases until the fan has reached its maximum rate of revolution. Additional parameters may be provided as triggers for messages or alarms. For example, if the ambient air temperature exceeds a predetermined parameter or the exhaust fan is spinning at an unacceptable rate, a message or alarm may be generated. A computer is sometimes connected to a controller to program its parameters, direct its behavior, and retrieve and display its status information, messages, and alarms.
Controllers can work alone or in clusters. If more than one controller is utilized, a master controller coordinates the efforts of the others. In some applications, slave controllers communicate with the master controller via a Local Area Network (LAN) such as an RS485 based LAN. If intra-communication is desired between master controllers, an Ethernet based LAN may be used.
In some applications, controllers may be distributed throughout large industrial or commercial buildings. In other applications, large distances may geographically separate controllers. In the former, controllers may be connected using either wired networks or wireless communications networks such as that embodied by IEEE standard 803.3 or 802.11. In the latter, telecommunications systems such as modems, DSL, cable, and satellite communications are the prevalent methods of connecting controllers.
With the advent of the Internet, it has become possible to connect controllers together using the World Wide Web (WWW). The Internet is formed by interconnecting communications devices such as switches, routers and servers. Information is carried via fiber-optics, phone lines, cable lines, microwave transmission, wireless digital radio transmission, and satellite communication. The Internet is a layered network communication system governed by the Open Systems Interconnection (OSI) model. Messages are sent over the Internet using transmission protocols (the fourth layer of the OSI model) such as Transmission Control Protocol/Internet Protocol (TCP/IP) or User Datagram Protocol/Internet Protocol (UDP/IP). The highest layer of the OSI model involves application software. Web browsers are utilized to convert messages into a human readable format.
To facilitate remote access, web servers are connected to controllers. A common web server includes a standard or industrial grade single-board computer, a connection to the Internet, access to an Internet Service Provider, and a means for communicating with the controller. Additionally, applications software is needed to both access the Internet and communicate with the controller. In some cases, this software requires an additional licensing fee.
Once a web server has been connected to a controller, it is a straightforward matter to provide access to the controller from another remote computer from practically any remote location over the Internet, as shown in FIG. 1. One or more Clients 10 provide user access to the Internet 12 in order to communicate with one or more controllers 14 through a web server 15. In this manner, a user may direct the behavior of the controller and receive updates on status information, messages, and alarms. FIG. 2 illustrates some examples of clients, such as a personal computer 16, an Internet-ready personal digital assistant (PDA) 18, or an Internet-ready wireless telephone 20.
While convenient, remotely accessing a controller through the Internet is not without certain problems. The first is a severe reduction in security, as it is relatively easy to gain unauthorized access to the controller""s web server. The second is that attaching a standard web server to each controller, or even limiting this to each master controller, is a significant investment of capital as each web server requires its own computer. Therefore, it is desirable to provide a means for providing remote access and control of distributed controllers over the Internet while maintaining security and minimizing the cost of associated web servers.
This invention is based on utilizing an Internet Hub to intercede in communications between Clients and Local Control Systems (LCS). A Local Control System includes at least one Master Controller and may include one or more Slave controllers. The resource intensive web server, formerly comprising a full-fledged computer, has been replaced with a small, inexpensive microprocessor based device.
One aspect of this invention is a means for remotely accessing Local Control Systems over the Internet while maintaining security. To this end, Clients are not permitted to directly access the controllers and may communicate only with the Internet Hub. Likewise, the scaled-down Web Servers only communicate with the Internet Hub on one side and the controller on the other. Additionally, a Web Server will only accept messages from authorized Internet Hubs. This maintains security and prevents unauthorized access of the Local Control System.
Another aspect of this invention is to reduce the hardware, applications software, and the associated cost required to remotely access Local Control Systems. The Internet Hub is used to remotely install programs and update parameters in individual controllers. It also retrieves status information from the controllers, over the Internet. This eliminates the need for a computer, applications software, and their associated costs at each Local Control System. In order for a user to monitor a controller, he must first access the Internet Hub which, in turn, accesses the Local Control System. Likewise, in order to program or update a controller, a user must send his requests to the Internet Hub where they are repackaged and retransmitted.
Yet another aspect of this invention is to provide a means of notifying users if established operating parameters have been exceeded by Local Control Systems. The Master Controller is responsible for providing regular updates of status information, messages, and alarms to the Internet Hub. Messages and alarms received by the Internet Hub are interpreted and then dispersed to users as e-mail, faxes, SMS messages, or phone calls.
Various other purposes and advantages of the invention will become clear from its description in the specification that follows and from the novel features particularly pointed out in the appended claims. Therefore, to the accomplishment of the objectives described above, this invention comprises the features hereinafter illustrated in the drawings, fully described in the detailed description of the preferred embodiments and particularly pointed out in the claims. However, such drawings and description disclose just a few of the various ways in which the invention may be practiced.